I found source of raw milk and i want to adjust the culture usage.I am using Danisco culture (MM100, TA061, LH100) and making cheese with 4G of milk.With the store regular milk i am using 1/4 tsp (1.25ml) for 4G. Should i change it ?

Well, some suppliers of cultures say you have to use half of the amount, but I noticed myself that I get the best results when I stick to the recipe. All recipes I've seen only add CaCl when no raw milk is used and don't reduce the amount of culture. But when I calculate the amount of culture I need with the amount of raw milk I have, I tend to round the amount downwards...

I don't adjust the culture. I did at one time and ended up with a bunch of cheese that did not age right because it doesn't have enough culture. Every cheese I made from mesophillic culture last year. I have a cave full of year old cheddar that has that twangy I'm not ready to eat taste to it.

One thing I have seen as a difference between raw and store bought milk is the amount of rennet you can use. For 2 gallon make I can use 1/4 tsp of single str veal rennet, but for store bought I have to use 5/16-3/8 tsp to get the same flocculation.

If you use 1/4 tsp of culture for 4 gallons of storebought milk, then I would suggest the same amount for raw milk...what you will see is your initial pH drop a bit sooner with the raw milk. If you have a pH meter, just keep an eye on your pH more often until you get used to it. If you dont use a meter, then you might consider reducing the innoculation time by 25% or so...but that's just what I experience with the raw milk I work with....your results my vary.

My experience (mine also lists a much larger amount for 2 gallons) has been to get a 15 minute flocc with raw milk to use 1/4 tsp....if I use 1/4 tsp with store bought milk I get a 20 minute flocc. I think I started off using 3/8 tsp with 2 gallons and I got a flocc of less than 10 minutes.